U.S. Pat. No. 4,230,549 purportedly discloses polymer membranes to be used in electrochemical cells produced by radiation grafting techniques.
U.S. Pat. Nos. 6,225,368 and 6,387,964 purportedly disclose monomer-grafted cross-linked polymers made by radiation cross-linking and grafting. In some embodiments, the monomer-grafted cross-linked polymer may be a fluoropolymer. In some embodiments, the monomer-grafted cross-linked polymer may then be sulfonated and used as an ion-exchange membrane in an electrochemical cell.
U.S. Pat. No. 6,255,370 purportedly discloses a solid polyelectrolyte fuel cell comprising a solid polyelectrolyte membrane, where the water content of the solid polyelectrolyte membrane is greater adjacent to the negative electrode. In one aspect, water content is purportedly controlled by controlling the degree of crosslinking in the membrane. The reference states, “when side chains are introduced into the film of a main chain copolymer, the material for the side chains or the crosslinking material is contacted with only one surface of the film, whereby the concentration of the side chains thus formed in the film or the degree of crosslinking in the film may be controlled in the intended manner.” ('370, col. 5, Ins. 57–61). Such treatment is followed by sulfonation. ('370, col. 6, Ins. 31–48).
U.S. Pat. No. 5,260,351 purportedly discloses perfluoroelastomers cured by radiation in the absence of curing agents. The reference purportedly relates to curing of fully fluorinated polymers, such as those prepared from tetrafluoroethylene, a perfluoralkyl perfluorovinyl ether, and cure site or crosslinking units providing at least one of nitrile, perfluorophenyl, bromine or iodine in the resulting terpolymer.